A flotilla from China’s navy appeared in American waters in early September, a few weeks before President Xi Jinping’s Sept. 24 visit to Washington. Indeed, Chinese Communist Party chieftains evidently instructed warships to take shortcuts — lawful ones, I hasten to add — through U.S. territorial waters in the Aleutians, off the coast of Alaska. Five vessels cruised the Bering Sea in early September — and elicited a fittingly low-key response from Washington: “China is a global navy,” declared one U.S. Navy spokesman, “and we encourage them and other international navies to operate in international waters as long as they adhere to safe and professional standards and maritime laws of the sea.”

Why would China go to the trouble and expense of mounting an expedition to the northern climes in the Western Hemisphere? Because it sees value in staging a presence in distant waters. And because it can: Beijing no longer depends completely on its oceangoing battle fleet to ward off threats in China’s seas. It can now rain long-range precision firepower on enemy fleets from land. Ergo, the People’s Liberation Army Navy (PLAN) fleet can cruise the far reaches of the Pacific and Indian oceans or even beyond, without forfeiting China’s interests in waters close to home. For China, the upsides of far-ranging maritime strategy are many and compelling, the downsides fewer and fewer. The PLAN’s Aleutians sojourn is the latest expression of Xi’s project to make China, a traditional continental power, into what he calls a “true maritime power” — and helping the nation fulfill its “Chinese dream.” Such aspirations will form an undercurrent to discussions between him and U.S. President Barack Obama. The takeaway? A new age of Chinese bluewater assertiveness is upon us.

What does Beijing stand to gain from a venturesome maritime strategy? A lot. Consider the location of its recent foray: The Bering Strait constitutes the most convenient entryway to the Arctic Ocean for Chinese merchant and naval vessels. Assuming the ice recedes as climate change advances, polar shipping routes will prove shorter and less convoluted — and thus less expensive and troublesome — than current alternatives. Consequently, it makes perfect sense for the PLAN to establish a presence along prospective sea lanes to Eurasia’s north.

Next, there are benefits to the navy itself. Sailing far-off waterways bolsters seamanship, tactical skill, and élan. Sailors hone their proficiency not by sitting in port — doing what idle youth do — but by riding the waves. If China wants the PLAN to become a fighting force on par with the U.S. Navy, the Japan Maritime Self-Defense Force, and other competitors for nautical preeminence, it needs the fleet to undertake deployments of increasing ambition, complexity, and geographic scope.

Until recently, naval officials were cautious about dispatching task forces beyond the Western Pacific and China seas. This changed, however, as the fleet matured in hardware terms. The finest weapon is no better than its operator. Now that the PLAN appears largely satisfied with its weaponry, it’s time to refine the human factor. Hence PLAN task forces are out and about on the seven seas more — not just the recent trip to the Aleutians, but also a September 2015 port call in Egypt, a May visit to the Black Sea, and assorted other naval diplomatic endeavors. This should be familiar to U.S. seafarers from their own coming out as a great navy a century ago, when their Great White Fleet circumnavigated the globe. Tend to materiel, tend to people: That’s wholesome goodness from a strategic standpoint.

The copycat factor

Apart from all this, Xi & Co. may have hoped to advance China’s cause in home waters by needling the United States in its home waters. Chinese officials and military officers commonly assume that Americans would never tolerate in their near seas what the U.S. Navy does in China’s near seas — sending surveillance planes along the coast, conducting underwater surveys, flying tactical aircraft from carriers, and the like. That’s why they’re forever invoking the Monroe Doctrine, or the Cuban missile crisis, or some other episode from U.S. history that supposedly proves that the United States claims the right to proscribe certain actions in its maritime environs.

As a matter of reciprocity, the Chinese insist that Washington afford fellow great powers the same prerogative in their neighborhoods. And China dearly wants to make the rules governing military activities in the China seas. In particular, Beijing wants to bar the South China Sea to foreign surveillance flights, underwater surveys, and aircraft carrier flight operations — allowing only passage through regional seaways from point A to point B. The operations that party potentates want to forbid are codified in customary and treaty law. Letting China do away with them would abolish freedom of the sea in that waterway. Foreign shipping would use the sea lanes only at Beijing’s sufferance.

Over time, relinquishing freedom of the sea in Southeast Asia might degrade the principle of freedom of the sea worldwide. It might discredit it altogether. No longer would the South China Sea be a maritime commons — and that would embolden powerful predators elsewhere around the globe to lay claim to their own adjacent waterways. Today, the South China Sea. Tomorrow, the Black Sea or Persian Gulf?

Still, if Beijing hopes to goad Washington into a hissy fit or impel it to abridge U.S. naval operations along the Asian periphery, it’s apt to be disappointed. One suspects Chinese officials are guilty of mirror imaging: assuming Americans see the world the same way the Chinese do and will respond the way the Chinese do to the actions of others.

We sail it, we own it

Seldom is that a safe assumption. Americans don’t take the same proprietary attitude toward the sea that the Chinese do. They barely think about the sea at all. (That body of water to our south is the Gulf of Mexico, for Pete’s sake!) Even at the height of U.S. activism under the Monroe Doctrine in the 19th century, the United States didn’t attempt to claim the Gulf of Mexico or the Caribbean Sea as sovereign property. That makes a marked distinction with China, which regards the South China Sea as “blue national soil”: territory that belongs to China and where Chinese domestic law rules.

Attitudes toward the sea aside, the Cold War is the historical episode that illustrates how U.S. officialdom will likely respond to PLAN voyages in the Americas. Washington views the presence of foreign navies near U.S. shores as the price of doing business on the briny main. Freedom of the sea is a matter of reciprocity. Abridge maritime liberties for others and they’re likely to abridge them for you.

The Soviet navy, for instance, routinely operated in the near seas off the United States during the Cold War. Submarines executed nuclear deterrent patrols offshore. Soviet spy ships (known as auxiliary general intelligence ships, or AGIs) and fishing trawlers packed with electronic eavesdropping gear shadowed U.S. naval task forces. So omnipresent were AGIs that more than one U.S. commander reportedly called up a Soviet ship when it approached and assigned it a station in the fleet. The AGIs maneuvered with the U.S. vessels so no one collided during changes of course or speed. In effect, it became a companion to a hostile fleet. There was a measure of comity even between fierce competitors.

China has yet to acclimate to the rules of the nautical game. Why? Because continental powers like China tend to think about the sea differently than natural seafaring states like the United States or Great Britain. Where nautical peoples see a commons — an ungoverned space, open for the free use of all — terrestrial peoples see national territory, to be governed as though it were dry land. A chasm separates Chinese from Western worldviews.

China’s land-bound mindset

Nor did China’s Cold War experience much change its land-bound mindset. The nation faced inward during Mao Zedong’s 1949 to 1976 reign, in an effort to make itself a modern industrial power in a hurry. Its navy was hemmed in behind an offshore island chain occupied by U.S. allies, and thus had to content itself with defending China’s seacoasts against amphibious invasion. Beijing was increasingly obsessed with strategic competition with the Soviet Union and gazed northward across the Sino-Soviet land frontier rather than turning seaward. Until the launch of China’s reform and opening project in the late 1970s, China kept its focus largely on land. Beijing never acculturated to high-seas strategic competition the way the United States and Soviet Union did.

But Beijing now seems set on a different course. Chinese officials have gone on record with their maritime territorial claims so often and so vociferously that they would make them themselves look weak and feckless before their own people should they relent: It’s hard to imagine them abandoning their challenge to maritime freedoms now. Inflexible public commitments — the South China Sea “belongs to China” being a recent one — have a way of tying officials’ hands.

If Beijing has ample reason to undertake high-seas enterprises, here’s why it can. The weapons on display during Beijing’s Sept. 2 military parade marking Japan’s surrender in World War II revealed why party leaders feel comfortable dispatching naval flotillas — assets built to protect the motherland while managing events in maritime Asia — to remote waters: They no longer see much risk in doing so. Owing to advances in technological wizardry, elements of the PLAN battle fleet can ply the seven seas without fear of compromising security closer to home.

Simply put, the land-based military (the People’s Liberation Army, or PLA) can increasingly face down challenges to Chinese interests on the high seas without resorting to the oceangoing PLAN fleet. Throughout history, it has generally taken a navy to beat a hostile navy. Technology is changing that. Today China’s array of “anti-access/area-denial” defenses — its shore-based arsenal for molding events at sea — is mature enough to discourage all except the most serious challenges.

Gun running

This opens up beguiling strategic vistas before Beijing. The PLAN fleet can cruise within range of anti-ship cruise missile and ballistic missile batteries positioned along the Chinese shoreline, adding heavy-hitting land-based firepower to its own. And that’s long-range precision firepower. The anti-ship ballistic missiles on display during the Sept. 2 parade can reportedly strike as far away as U.S. bases on Guam in the Western Pacific.

Also in the PLA’s panoply are combat aircraft toting anti-ship cruise missiles. These, too, can strike out hundreds of miles from Asian shorelines. Augmenting land-based air assets and missiles are submarines and surface patrol craft useful for picket duty — standing guard offshore, much as sentries patrol an army’s periphery to ward off assault. These craft pack a serious punch. This makes for a dense network of defenses — and a nightmare for U.S. and allied naval commanders trying to defend allies, uphold freedom of the sea, and accomplish other worthwhile goals.

Land-based implements of sea power, then, constitute a great equalizer for the PLAN, helping close the firepower gap between China and America’s navies. Think about the benefits anti-access confers. Shore-based forces could wallop the U.S. Pacific Fleet during a fight in the Western Pacific, augmenting the PLAN fleet’s own striking power. That’s why ship-for-ship and plane-for-plane comparisons between the U.S. and Chinese navies mislead: The proper comparison is between part of the U.S. Navy (the part in the Pacific) and the whole of the PLAN — along with the PLA Second Artillery Corps, or ballistic missile force, and air force and navy combat aircraft capable of operating over water. That’s 60 percent of the U.S. Navy against a peer navy, army, and air force — on the opponent’s home turf.

Indeed, the PLAN conceivably might not even have to get involved in a fight. PLA commanders have the luxury of pummeling regional antagonists — notably the Japan-based U.S. 7th Fleet and Japan Maritime Self-Defense Force — even if China’s battle fleet never gets underway. Allied fleet bases lie well within reach.

That prospect gives Washington, Tokyo, and other potential foes second thoughts about making mischief at China’s expense. If the anti-access network plays out as intended, Beijing will feel increasingly confident about dispatching the battle fleet to the Indian Ocean, the Persian Gulf, or even remoter expanses such as the Mediterranean or Atlantic.

For China, then, an expansive maritime strategy starts with guarding the home front. If PLA rocketeers and aviators can pound seaborne antagonists from shore, why not send the PLAN bluewater fleet out of area to do business the party leadership deems important?

Free-rangers on the high seas

Look back in history to glimpse how this defensive architecture works. A century ago, sea-power pundit extraordinaire Alfred Thayer Mahan took the Imperial Russian Navy to task for timidity, risk aversion, and defensive-mindedness. He did so while critiquing the Russo-Japanese War of 1904-1905, a conflict that saw the Imperial Japanese Navy litter the East Asian seafloor with wreckage from two Russian fleets while seizing command of the sea. Mahan lambasted Russian naval commanders for using their Pacific squadron as a “fortress fleet” rather than a free-range fighting force.

Naval warfare is not for the meek. In theory, fighting ships are put to sea to defend important seaports against foes menacing from the sea. In practice, though, timid commanders like in imperial Russia tend to let the port protect them. It’s perverse when the protector becomes the protected — and that’s the fallacy Mahan was railing against.

Why shelter under the fort’s guns (or missiles and combat aircraft in this ultramodern age)? Simple: Fortresses are big compared to ships. The biggest ship is small, with limited space to house heavy weaponry and ammunition. Bases have room for bigger, heavier-hitting weapons fed by larger stockpiles of ammunition. That’s doubly true today, when anti-ship missiles mounted on trucks can be positioned anywhere along a shoreline. Fortress China furnishes more than ample ground for staging anti-access armaments.

Small wonder that Lord Horatio Nelson, the victor of Trafalgar, once proclaimed that “a ship’s a fool to fight a fort.” Such fights are typically lopsided in favor of the fort’s gunners. Small wonder, too, that the Imperial Russian Navy sheltered under the guns of Port Arthur, on the Liaodong Peninsula in northeast China — letting that shore-based firepower defend them from Adm. Togo Heihachiro’s superior Combined Fleet. Playing it safe shielded the tsar’s pricey battleships, cruisers, and destroyers from Japanese marksmanship.

The virtues of offense

Yet playing defense only worked within a small arc of offshore waters. The range of even the finest artillery of the day was under 10 miles. Pick up a compass, set it to 10 miles, and trace a circle around Port Arthur on the map. That’s a remarkably cramped sea area — too little for a great fleet to maneuver. If staying within range of Port Arthur’s artillery fended off Togo & Co. for the most part, then it also fettered the Russian squadron’s freedom of maneuver — and its commanders’ offensive options.

Such constraints are anathema to sea warriors. Dueling the main enemy fleet on the open sea is the hallmark of Mahan’s theory of sea combat. Commanders who make preventing an enemy fleet from pummeling them their chief goal transform the enterprise from offense into defense. Active strategy becomes passive. Winning takes second place to surviving. And in all likelihood, the goals entrusted to the fleet by senior military or political leaders go unfulfilled.

Suppose a latter-day counterpart to the Russo-Japanese War took place, a regional conflict in maritime Asia. And suppose land fortifications — today’s answer to Port Arthur — were outfitted with the latest in anti-ship military technology. What if the fort’s “guns” could strike not a few miles but hundreds of miles out to sea, targeting fleets operating not just immediately offshore but between Asia’s first and second island chains?

It’s doubtful Togo could have kept up a close blockade of Port Arthur under constant fire. This casts Mahan’s critique in a new light. He was correct in saying that depending on the fort kept the fleet on a short tether — but technological change has rendered his point moot. Long-range precision firepower manifest in land-based missiles and aircraft — the ultramodern descendants of Port Arthur’s gunnery — could clear vast swaths of the Western Pacific of hostile shipping. At a minimum, shore-based aviators and rocketeers could exact a heavy toll from fleets that dared steam into China’s contested zone.

The fortress fleet

With apologies to boxing legend Jack Dempsey, the best offense is a good defense for China — not the other way around. Solid defense close to home, in other words, frees the PLAN battle fleet to prowl the China seas and much of the Western Pacific, executing offensive missions while summoning fire support from airfields and mobile missile batteries should the need arise. Shore defenses constitute a liberating force for PLAN skippers, not a millstone the way they were for Russian seafarers a century ago.

In short, the day of the fortress fleet may have dawned, courtesy of high technology. And the benefits of access denial extend beyond the Western Pacific. If Beijing is confident enough in its shore-based defenses, it could deploy part or all of its fortress fleet as an out-of-area, expeditionary fleet. PLAN task forces could venture beyond the protective anti-access/area denial cocoon on errands the party leadership deems important. Just look at the PLAN’s excellent Aleutians adventure as part of this upswing in the vigor and ambition of Chinese naval operations.

Fortress China is a now continental-cum-maritime power able to shape events at sea from the land: a sea power that enjoys the liberty to embrace a forward-leaning marine strategy. PLAN flotillas will become an increasingly common sight in seaports throughout maritime Asia — and beyond. That’s something to ponder as Xi goes to Washington. No longer is the relationship between China and the United States the relationship between a land and a sea power: It’s now a relationship between two sea powers.